Aluminum phosphates, compositions comprising aluminum phosphate, and methods for making the same

Abstract

APs are made by binary condensation via base-to-acid or acid-to-base routes. In the base-to-acid route, an aluminum hydroxide slurry is added to phosphoric acid that reacts to produce an aluminum phosphate condensate. In the acid-to-base route, phosphoric acid is added to an aluminum hydroxide slurry that reacts to produce an aluminum phosphate condensate. In an alternative base-to-acid route, an acidic aluminum phosphate is first made by adding phosphoric acid to a first amount of aluminum hydroxide slurry, and such acidic aluminum phosphate is added to a remaining amount of aluminum hydroxide slurry to react and produce an aluminum phosphate condensate. The reactions can be controlled to form an in-situ layered aluminum phosphate. So-formed APs can be amorphous, crystalline, or a combination thereof, and have low oil absorption and surface area, making them particularly useful in such end-use applications as extender pigments in coating compositions, replacing up to 70 wt % of TiO 2 .

1 . A method for making aluminum phosphate comprising the steps of:
 combining a slurry of aluminum hydroxide and water with phosphoric acid to form a mixture; and   reacting the mixture to form aluminum phosphate particles, wherein the aluminum phosphate particles comprises amorphous aluminum phosphate.   
     
     
         2 . The method as recited in  claim 1  wherein during the step of reacting the volume of the mixture is maintained at a constant level. 
     
     
         3 . The method as recited in  claim 1  wherein during the step of reacting moisture is allowed to escape. 
     
     
         4 . The method as recited in  claim 1  wherein the slurry comprises about 10 to 40 percent by weight aluminum hydroxide. 
     
     
         5 . The method as recited in  claim 4  wherein the slurry comprises about 25 percent by weight aluminum hydroxide. 
     
     
         6 . The method as recited in  claim 1  wherein during the step of combining, the aluminum hydroxide slurry is added to the phosphoric acid. 
     
     
         7 . The method as recited in  claim 5  wherein the slurry is added for a period of about 10 to 60 minutes. 
     
     
         8 . The method as recited in  claim 1  wherein before the step of combining, the slurry is heated to an elevated temperature. 
     
     
         9 . The method as recited in  claim 1  wherein before the step of combining, the slurry is formed using heated water to facilitate dispersion of the aluminum hydroxide to form the slurry. 
     
     
         10 . The method as recited in  claim 1  wherein the slurry is at an elevated temperature when combined with phosphoric acid. 
     
     
         11 . The method as recited in  claim 10  wherein the slurry is heated to a temperature of about 30 to 95° C. 
     
     
         12 . The method as recited in  claim 11  wherein the slurry is heated to a temperature of about 65° C. 
     
     
         13 . The method as recited in  claim 1  wherein the step of reacting takes place between about 60 to 120° C. 
     
     
         14 . The method as recited in  claim 13  wherein the elevated temperature is about 95° C. 
     
     
         15 . The method as recited in  claim 1  further comprising, after the step of reacting:
 separating the aluminum phosphate particles from a reaction solution; and 
 drying the aluminum phosphate particles. 
 
     
     
         16 . (canceled) 
     
     
         17 . The method as recited in  claim 1  wherein the aluminum phosphate particles consist of amorphous aluminum phosphate. 
     
     
         18 . The method as recited in  claim 1  wherein the aluminum phosphate particles comprise crystalline aluminum phosphate. 
     
     
         19 . The method as recited in  claim 1  wherein the aluminum phosphate particles comprises a combination of amorphous aluminum phosphate and crystalline aluminum phosphate. 
     
     
         20 . A chemical composition comprising a binding polymer and the aluminum phosphate prepared according to  claim 1 . 
     
     
         21 . The chemical composition as recited in  claim 20  further comprising a pigment material different from the aluminum phosphate. 
     
     
         22 . The chemical composition as recited in  claim 21  wherein the aluminum phosphate comprises less than about 70 percent by weight of the total weight of the pigment materials. 
     
     
         23 . The method as recited in  claim 1  wherein the aluminum phosphate particles have an oil absorption of less than about 50. 
     
     
         24 . The method as recited in  claim 1  wherein the aluminum phosphate particles have a surface area of less than about 20 m2/g. 
     
     
         25 . A method for making aluminum phosphate compositions comprising the steps of:
 combining a slurry of aluminum hydroxide and water with phosphoric acid to form an acidic aluminum phosphate solution;   combining the acidic aluminum phosphate solution with aluminum hydroxide slurry to form a mixture; and   reacting the mixture to form aluminum phosphate particles.   
     
     
         26 . The method as recited in  claim 25  wherein during the step of combining the acidic aluminum phosphate solution with aluminum hydroxide slurry there exists a sufficient aluminum content in the mixture to achieve a desired P:Al ratio in the range of from about 0.1 to 1.5 during the step of reacting. 
     
     
         27 . The method as recited in  claim 25  wherein before the step of adding, the phosphoric acid is diluted with water. 
     
     
         28 . The method as recited in  claim 25  wherein during the step of reacting, the volume of the mixture is maintained at a constant level. 
     
     
         29 . The method as recited in  claim 25  wherein the slurry comprises about 10 to 40 percent by weight aluminum hydroxide. 
     
     
         30 . The method as recited in  claim 29  wherein the slurry comprises about 25 percent by weight aluminum hydroxide. 
     
     
         31 . The method as recited in  claim 29  wherein the step of reacting takes place at an elevated temperature. 
     
     
         32 . The method as recited in  claim 31  wherein the elevated temperature is about 95° C. 
     
     
         33 . The method as recited in  claim 25  further comprising before the step of reacting, adding a calcium-containing ingredient to the mixture. 
     
     
         34 . The method as recited in  claim 25  further comprising, after the step of reacting:
 separating the aluminum phosphate product from a reaction solution; and 
 drying the aluminum phosphate particles. 
 
     
     
         35 . (canceled) 
     
     
         36 . The method as recited in  claim 25  wherein the acidic aluminum phosphate solution is amorphous aluminum phosphate. 
     
     
         37 . The method as recited in  claim 25  wherein the aluminum phosphate particles consist of amorphous aluminum phosphate. 
     
     
         38 . The method as recited in  claim 25  wherein the aluminum phosphate particles comprise crystalline aluminum phosphate. 
     
     
         39 . The method as recited in  claim 25  wherein the aluminum phosphate particles comprise a combination of amorphous aluminum phosphate and crystalline aluminum phosphate. 
     
     
         40 . The method as recited in  claim 25  wherein the aluminum phosphate particles have an oil absorption of less than about 50, and a surface area of less than about 20 m2/g. 
     
     
         41 . A chemical composition comprising a binding polymer and the aluminum phosphate prepared according to  claim 25 . 
     
     
         42 . The chemical composition as recited in  claim 41  further comprising a pigment material different from the aluminum phosphate. 
     
     
         43 . The chemical composition as recited in  claim 42  wherein the aluminum phosphate comprises less than about 70 percent by weight of the total weight of the pigment materials. 
     
     
         44 . The method as recited in  claim 25  wherein during the step of adding, the acidic aluminum phosphate solution has greater than a 2:1 molar ratio of P:Al. 
     
     
         45 . The method as recited in  claim 25  wherein during the reacting step the volume of the mixture is variable. 
     
     
         46  to  78 . (canceled) 
     
     
         79 . The method as recited in  claim 1  wherein during the step of combining, the phosphoric acid is added to the slurry. 
     
     
         80 . The method as recited in  claim 25  wherein during the step of combining, the phosphoric acid is added to the slurry. 
     
     
         81 . The method as recited in  claim 25  wherein during the step of combining, the slurry is added to the phosphoric acid.